Aqueous emulsion paint



Patented Nov. 11,

PATENT OFFICE 2,430,828 AQUEOUS EMULSION PAINT Marvin 'r. Schmidt,Chicago, and John K. wise,

Evanston, 111., assignors to United States Gypsum Company, Chicago,111., a corporation of Illinois No Drawing. Application February 23,1944,

SerialNo. 523,580

1 '10 Claims. This invention relates to an improvement in the .art ofmanufacturing colored emulsion paints, sometimes referred to as resinemulsion paints, and more particularly to a paint which is uniform incolor and free from streaking and blotchlng when applied to ordinarysurfaces.

It is the purpose of this invention to produce a colored emulsion paintwhich is substantially free from blotching and streaking when applied inthin film form, particularly to surfaces which are high in absorptionsuch as plasterboard or a lime putty finish.

It is well known that colored emulsion paints, such as those made usingalkyd resins, as well as other film forming materials, will sometimesshow differences in color when applied over surfaces exhibitingdifferent degrees of suction in various areas, though the paint itselfis uniform; and in addition, these paints often show differences ofcolor as streaks along the path of the brush when the paint is appliedover such surfaces. When a painted surface exhibits either brush streaksor blotches a very undesirable condition exists which is a consistentcause for complaint in the field. Unfortunately, repainting thenon-uniform colored surface does not always result in an improvement ofthe surface, but in many cases magnifies the difilculty. The exact causeof these conditions is not known but it is believed due to irregularabsorption of the surface.

In the description of this invention the term blotching is defined tomean the variation in shade in localized areas different from the field1 color when the same shade of paint is used streaking" is mean thecolor variation which follows the path of the brush strokes in parallellines like the ridges and depressions following the brush though theremay not be such ridges and depressions.

This difficulty of streaking and blotching can be overcome by firstthoroughly sealing or priming the surface with a varnish type ofsurfacing material. This treatment is expensive when applied only forthis purpose as in general it is not ordinarily needed to accomplish anyother purpose. In fact, many of the walls to which an emulsion paint isto be applied are green" and hence cannot be properly sized until dry.One of the outstanding advantages of an aqueous emulsion paint is thatit can be applied to green walls without previous dryin and to dry andsize the wall so that it can be painted would be doing away with 6 or;tof the big advantages in using this type of It has been discovered thatby the simple addition of certain materials this difficulty of streakingand blotching can be practically completely eliminated. Thus ifdifficulty of this type is encountered in actual field application, itcan be overcome merely by mixing a small quantity of the inhibitingmaterial into the paint.

Thematerials that accomplish the purpose of this invention were obtainedas a result of a great number of trials using various types ofmaterials. No predictions arising out of knowledge commonly known tothose skilled in the art could be made. No explanations can be made asto why only certain few materials will work satisfactorily while a greatrange of other materials will not. Numerous theories were considered,but no data to support them could be evolved. I

Only a very limited number of materials can be used for the purpose. Oneclass of materials which has beenfound satisfactory is certain fattyacid esters of polyethylene glycols. The use of this class of materialsto prevent streaking and blotching in colored emulsion paints is thesubject of a copending application SerialNo. 523,581 of one of the jointinventors of this application. Another class of materials, which hasbeen found satisfactory is the lower saturated aliphatic alcohols offrom 3 to 5 inclusive carbon atoms, except isopropyl, tertiary butyl andtertiary amyl alcohol. Diacetone alcohol is also effective. The aboveare the only known materials which will give commercial satisfaction inovercoming the disadvantages of streaking and blotching. The use ofthese alcohols is the subject of this invention.

In carrying out this invention, it is preferred to add the material tothe paint during its formulation as a morecomplete and accurateintermixing can be accomplished; though it is within the scope of thisinvention, and sometimes necessary. to add the alcohols to the paintlnthe field. For purpose of illustrating the preferred method ofcarrying out this invention in the following exformulation.

ample, the material will be added during 3 The following example clearlydescribes a paint composition which but for the inhibiting materialincorporated therein will show pronounced streaking and blotching whenapplied to many types of surfaces.

Emulsion Pounds Ester gum-linseed oil binder 166 6% cobalt drier 8Casein solution, 20% solids 340 Paste paint Pounds Emulsion 514.0Phthalocyanine blue 31.6 Cadmium yellow 31.6 Bone black 4.75 Titaniumdioxide 900 Pine oil 25 Fine Mica I 60 Water approximately 350 Fusel oil35 to 70 The ester gum-linseed oil binder is prepared by heating to atemperature of 580 degrees F. for 4 of preparing an emulsion, with thecasein s olution to form a binder. Most any type of casein solution canbe used. A suitable casein solution is one which is described in U. S.Patent No. 2,154,362. This can be used to advantage as it is stable fora considerable length of time to deterioration due to aging. However,the preparation of casein or other protein solutions using alkalies suchas borax for use in emulsion paints is well established in the art and adetailed description of a procedure for making them need not be includedin the description ofthis invention,

For the sake of conveience for those who may not be familiar with thisart and with U. S. Patent No. 2,154,362, the following procedure, whichis based upon the above patent, can be used in preparing a caseinsolution. Following this patent the casein solution can be prepared bymixing 55 lbs. of commercial casein with 24 gallons of water withthorough stirring for a sufllcient length of time until a smooth mixtureof thoroughly soaked casein results. About 3 pounds and 6 ounces ofsodium stannate are dissolved in about 3 /2 gallons of water, while in aseparate container about 10 lbs. of borax are likewise dissolved inabout 2 /2 gallons of hot water. The

sodium stannate solution is then added to the casein mixture, withconstant agitation, and as soon as all of it has been added, the boraxsolution is then run into the mixture. An additional amount of, say, 3gallons of water may then be added and the mixing continued whileheating the mixture gradually to about 150 to 160 degrees F. or higher.The mixing is continued at the desired temperature until a smoothsolution results. Using the proportion above given, the solution will befound to exhibit an alkaline reaction equivalent to from about pH 8.0 topH 9.0. The ratio of casein to sodium stannate in the above formula issubstantially 100:6.2. The sodium stannate used has the folowingformula: NazSnO3.3HzO.

While casein is the preferred type of protein,

.other proteins may be used including those de' suitable type of mixer.

and other ingredients are added and mixed in a The fusel oil ispreferably added last. While fusel oil is used in the above preferredexample, it is not intended to limit this invention to this particularmaterial for other alcohols can be used, as will be more clearlydescribed later.

After the fuse] oil has been added and the mixing operation has beencompleted, the paste is then passed through a roller mill to insurecomplete dispersion of the pigments into the vehicle and to form a paintcompletely free from lumps.

Various types of pigments, fillers and other finely divided inorganicmaterial can be used in the preparation of paints which can be benefitedby this invention. However, it is necessary that some coloring materialbe present as streaking and blotching have not been observed to anygreat extent in white paints. Since water is the thinner, it is possibleto use a wide variety of low index of refraction materials such asclays, mica, etc., known in the trade as fillers or extenders to replacea certain amount of the more expensive higher index of refractionmaterials, known as pigments, such aslithopone and titanium dioxide, asrequired in an oil type oil-paint. Since both types of material can beused, in order to define these two types of material generically, theword pigment-fillers will be used in the forthcoming claims.

Paint prepared in the above manner will not exhibit the streaking andblotching eflects commonly associated with emulsion paints. This is donewithout any sacrifice in the desirable properties of this type ofmaterial and with only a slight increase in cost.

If the paint has already been prepared, and streaking and blotching areencountered, then about 4 to 8 ounces of fusel oil can be added pergallon. It may be expedient in many cases not to add the inhibitingmaterial until actual trouble is experienced as the difilculty is onlyoccasionally encountered. Amounts as low as one ounce per gallon havebeen found effective in some It is not the intention to limit thisinvention to the preferred embodiment set forth above for othersaturated aliphatic alcohols having 3 to 5 carbon atoms per molecule canbe used as well as diacetone alcohol. However, it has been found thatisopropyl, tertiary butyl and tertiary amyl alcohols for someunexplainable reason are unsatisfactory for carrying out the principlesof this invention, though their presence does not interfere with theeifectiveness of the other alcohols to any great extent. Examples ofsaturated aliphatic alcohols which can be used, including those of 3 to5 carbon atoms per molecule, are:

Propanol-1 Pentanol-3 Butanol- 1 2 methyl butanoll Butanol-2 3 methylbutanoll 2 methyl propanol--1 3 methyl butanol2 Pentanol-l 2-2 dimethylpropanol-l Pentanol-2 Diacetone alcohol emulsion paint comprising aprotein selected from the group consisting of casein and alkalidispersible vegetable protein derived from soybeans, a solvent for saidproteins, water, a water insoluble film forming material, coloredpigment and a a streaking and blotching inhibiting material sepaintis'encountered.- The regular commercial substance which will haveutility in a colored emulsion paint may be used. It is not necessarythat the material be a resin, though most of the emulsion paints incommon use contain'a resinous or polymerizable material, usuallyoleoresinous. Examples of some of the materials which can b incorporatedare: treated or untreated oils having drying properties, alky'd resins,phenol formaldehyde resins, the various esters of rosin, synthetic andnatural resins, such as congo gum, copal gum and manila gum. These canbe used alone, in combination, or with solvents; the particular mannerin which they are used as well as the addition of other materials suchas driers and the like are all within the skill of the art of which thisinvention is a part and need not be further described.

While, it is preferred to use casein or some other protein material,.such as Alpha protein derived from soya beans, as the emulsifying agent,it is not th intention to limit this invention thereby, for otheremulsifying agents which are compatible can be employed. The volatilealkali soaps are especially suitable for the purpose.

It will be found that paints prepared in accordance with the principleset forth in this invention can be applied .over practically any surfacewithout the danger of forming an appreciable amount of streaks orblotches. A uniform film will be obtained. Water paints appliedfollowing the principles set forth in this invention.

By way of summary this invention pertains to the prevention of colorbiotching and streaking in a colored aqueous emulsion paint byincorporating therein diacetone alcohol or a saturated aliphatic alcoholof from 3 to 5, inclusive, carbon atoms per molecule exceptingisopropyl, tertiary butyl and tertiary amyl alcohols. The non-aqueousvehicle may consist .of oils, varnishes, natural and synthetic resins orother water insoluble film forming material; these are preferablyemulsified by the use of casein or similar materials.

Although there has been disclosed a practical embodiment of thisinvention and specific exam-. pies and uses, which are given to insure aclear understanding of the essence of this invention, it is not theintention to be limited thereby for obviously many variations may bemade by those skilled in the art and still be within the scope of thisinvention which is only limited in extent by the forthcoming claims.

It is claimed: 1. A non-streaking, non-blotching, aqueous Pentanol-llected from thegroup consisting of Propano11 Pentanol-B Butanol-l2methylbutanol-l Butanol2 3 methyl butanol--1 3 methyl butanol-2 2-2dimethyl propanol-l Pentanol-2 Diacetone alcohol 2. The composition oi?claim 1 in which said water insoluble film forming material is an oilhaving drying properties. 1

3. The composition of claim 1 in which said water insoluble film formingmaterial is a resinpus. material selected from the group consisting ofsynthetic resins and natural resins, and a solvent for said resin.

4. The composition of claim 1 in which said water insoluble film formingmaterial is an ester of resin acids.

5. A non-streakin non-blotching, colored, aqueous emulsion paintcomprising a protein selected from the group consisting of casein and analkali dispersibie vegetable protein derived from soybeans, an'alkalinesolvent for said protein, water, a water insoluble fi1m formingmaterial, pigment-fillers at least one of which is colored,

2 methyl propanol--l and an alcohol selected from the group consist- 6.The composition of claim 5 in which from about 1 to. about 8 ounces ofsaid alcohol is used to each gallon of said aqueous emulsion paint.

7. The composition of claim 5 in which said alcohol is commercial amylalcohol.

8. The composition of claim 5 in which said alcohol is commercial butylalcohol.

9. The composition of claim 5 in which said alcohol isdiacetone alcohol.

10. An aqueous emulsion paint substantially free from streaking andblotching comprising a water insoluble film forming oleoresinous bindercomprising the product resulting from heating an oil having dryingproperties with a resin selected from the group consisting of syntheticresins and natural resins, an emulsifying agent comprising a proteinselected from the group consisting of casein and alkali dispersiblevegetable protein derived from soybean, an alkaline solvent for saidprotein, water, pigment-fillers, at least one of" which is colored, andan alcohol selected from the group consisting of 7 BEFEBEl N'CES crmnfile of this patent:

UNITED STATES PATENTS Number Name 4 Date Douty et a1 Oct. 2, 1945 Howaldet a1 Nov. 9, 1943 Number Name Date Clocker June 9, 1942 Cheetham et a1.Apr. 14, 1942 Thackston Apr. 9, 1940 Dreylink et a1 Feb. 20, 1940 FrlpkOct. 31, 1939 Scholz Apr. 11, 1939 Baird Mar. 31, 1936

